BN_num_bytes

BN_num_bits, BN_num_bytes, BN_num_bits_word − get BIGNUM size

 #include <openssl/bn.h>

 int BN_num_bytes(const BIGNUM *a);

 int BN_num_bits(const BIGNUM *a);

 int BN_num_bits_word(BN_ULONG w);

These functions return the size of a BIGNUM in bytes or bits, and the size of an unsigned integer in bits.

BN_num_bytes() is a macro.

The size.

bn(3)

BN_num_bytes(), BN_num_bits() and BN_num_bits_word() are available in all versions of SSLeay and OpenSSL.